The European Asphalt Pavements Association and Eurobitume report of 2004 entitled Environmental Impacts and Fuel Efficiency of Road Pavements (Beuving et al., 2004) is one of the main sources forming the basis for this section of the present chapter.
Rolling resistance is one of the numerous factors of intense interest when considering the problem of fuel consumption while driving, especially in the context of SMA. Rolling resistance may be defined as the force necessary to move a vehicle along a pavement.
At a constant speed of 80 km/h, approximately 12% of the energy loss (fuel consumption) of a heavy truck is consumed in overcoming the rolling resistance; the energy spent on overcoming this resistance equals about 30% of the potential available mechanical power at the engine crankshaft (Sandberg, 2001).
Briefly, the rolling resistance is affected by microtexture, macrotexture, megatexture, and the unevenness of a wearing course.
According to Dutch research (Roovers et al, 2005), rolling resistance can be ranked by type of wearing course (results in cR[%]) as follows:
Cement concrete with burlap (smooth)—0.86 SMA 0/8—0.86
Double layer porous asphalt 2/6—0.97
Double layer porous asphalt 4/8—1.02
Cement concrete transversely brushed (rough)—1.04
Single layer porous asphalt 6/16—1.05
Dense AC 0/16—1.09
Mastic asphalt 0/11—1.18
Finally one should remember that rolling resistance measurements are strongly influenced by weather (e. g. sidewind velocity). Weather conditions could affect the test results.
Swedish investigations (Sandberg, 2001) have additionally pointed out that the pavement unevenness increases fuel consumption by as much as 12%, which seems to be a more significant factor than the type of asphalt surfacing.
